Mandibular advancement device with positive positioning hinge

ABSTRACT

The invention is an oral appliance for prevention of sleeping problems including snoring, sleep apnea and bruxism. Specifically, the appliance alters the position of the user&#39;s mandible, which is known as a method for reducing the restriction of the flow of air through the pharyngeal passageway. The appliance is a one-piece device molded from a flexible polymer such as Kraton®. It includes an upper maxillary tray and a lower mandibulary tray. Both upper and lower trays include inner and outer walls which increase contact area with the teeth. The hinge mechanism of the device includes a positive positioning system comprised of opposed interlocking ridges. The ridges serve to create offset between the position of the upper tray and lower tray relative to each other, therefore advancing the user&#39;s mandible. Additional features include airflow posts to keep the mouthpiece from sealing completely, a cleft contour, and a tooth retention tab.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of provisional patent applicationNo. 61/195,171, filed Oct. 3, 2008

FEDERALLY-SPONSORED RESEARCH

None

SEQUENCE LISTING

None

BACKGROUND

The present invention relates to devices for prevention of sleepingproblems including snoring and sleep apnea. Specifically, the device isan oral appliance which alters the position of the user's mandible.Advancing the position of the mandibular mouth structure relative to theposition maxillary mouth structure is known as a method of reducingsnoring and sleep apnea by reducing the restriction of the flow of airthrough the pharyngeal passageway. The decrease in air flow restrictioncauses a reduction in the vibration of soft tissue that's a cause ofsnoring, as well as reducing occlusion that's a cause of sleep apnea.

FIELD OF THE INVENTION

It is well-established that snoring and sleep apnea are sleepingproblems that effect the quality of life of many people. Snoring isgenerally caused by the vibration of soft tissue and tongue against theback of the throat, which can be caused by restricted airflow throughthe pharyngeal passageway. Both the person snoring and other personsnearby can be affected by the resulting noise.

The relaxation of muscles during sleep can allow the structures andtissues of the nose and mouth to fall backwards against the back wall ofthe throat. While partial airflow restriction results in snoring, morecomplete obstruction can result in sleep apnea, also known asobstructive sleep apnea (OSA). OSA can result in the stoppage ofbreathing for short periods, which causes the sufferer to gasp for air,causing a change in the contraction of muscles and resulting significantdisruptions in sleep patterns. With a lower quality of sleep, thesufferer may experience fatigue-induced problems such daytimesleepiness, depression, and other related problems. More severecomplications such as heart attack or stroke can also be associated withdecreased airflow and reduced blood-oxygen saturation levels.

Therefore, opening the pharyngeal passageway for increased airflow whilesleeping can eliminate or significantly reduce snoring and OSA, and theresulting benefits are apparent.

Numerous methods for preventing snoring and/or OSA currently exist. Onemethod is the advancement of the mandibular structure relative to themaxillary structure. It has been established since the 19^(th) centurythat advancing the mandible results in increased airflow through thepharyngeal passageway. Thus advancement of the mandible while sleepingcan reduce or eliminate snoring and/or OSA.

DESCRIPTION OF RELATED ART

Numerous devices exist to advance the position of the mandible, andtherefore prevent snoring and OSA. Such devices are in the form of aoral appliance worn by the user while sleeping. However, all suchdevices previously known face certain limitations. One common limitationis that custom molding is often required to shape the device to a user'steeth or mouth. This requires the expertise of a medical professionalsuch as a dentist, and is therefore expensive and time-consuming.Additionally, many devices restrict the physiological movement of theuser from freely opening and closing their jaw when the device is placedin the mouth. This is uncomfortable and unnatural for many users. Theupper and lower trays of many devices force the jaw in a fixed, nearlyclosed, or closed position. A device which, by design, is not allowed toclose completely would aid in the flow of air through the mouth.

U.S. Pat. No. 6,129,084 (Bergersen) describes an intra-oral device foradvancing the user's mandible. The device is comprised of two u-shapedplates joined to form a hinge. The lower plate includes a channel. Thislower plate channel has an inner wall (lingual wall), which faces theuser's tongue, and an outer wall (labial-buccal wall), which faces theuser's cheek and lips. Thus the user's mandibular teeth are cradled inthe lower channel. The upper plate contains an outer wall (labial-buccalwall), but does not include an inner wall (lingual wall). The lack of aninner wall is to position the user's tongue in contact with the lingualside of the user's maxillary teeth, meaning the inside of the user'supper teeth. The preferred embodiment of this device is molded frompliable material in one piece and uses a simple hinge mechanism. Thehinge is comprised simply of a thinning of the cross-section of themolded material, which allows the device to bend. It is described thatthe hinge may be sufficiently rigid to maintain a substantial gap in anopen position, even when the user applies considerable force.

This '084 device, however, faces numerous limitations. The simple hingemechanism is subject to wear as the pliable material is bent over manycycles of the user's mouth opening and closing. The mandibularadvancement the device provides is created solely by the position of thehinge. Fatigue of the, material, compounded by a lack of mechanicalreinforcement, may allow the simple living hinge to become sloppy andloose, rendering the device unable to properly advance the mandible. Inaddition, there's no mechanical element to prevent the device fromcompletely closing, causing upper surface 24 and lower surface 14 tobecome co-planar.

U.S. Pat. No. 6,055,986 (Meade) describes a mandibular advancementmouthpiece that includes a hard shell that holds a soft, moldablematerial. The soft material rests against the teeth. The device is madein two major halves, an upper member and a lower member. One embodimentcontains reciprocal surfaces 222 and 224 which fit together to fix therelative forward and backward positions of the upper and lower membersto each other. However, with this device the upper and lower members arenot connected or hinged to one another. Rather, this device relies onthe material being molded to the user's individual teeth and theresulting contact adhesion in order to stay in place in the mouth.

U.S. Pat. No. 6,170,485 (Orrico) also describes system with two halves.It also uses moldable inner trays to interface with the teeth. Itfurther describes tongues 30 and 32 which extend out of person's mouth.One tongue includes a plurality of holes 34, while the other tongueincludes a projection 36. The projection aligns with one of the holes tocreate mandibular advancement, with different holes creating differentamounts of advancement. However, with this device the upper and lowermember's are not connected or hinged to one another. Rather, this devicerelies on the material being molded to the user's individual teeth andthe resulting contact adhesion in order to stay in place in the mouth.

U.S. Pat. No. 5,829,441 (Kidd) also describes system with two halves. Italso uses moldable material to interface with the teeth. Means areincluded for adjustably advancing the user's mandible. However, thisdevice requires the user to sleep with their jaw in a fixed, clenchedposition. Many people find sleeping with their jaw in a fixed positionto be very uncomfortable, potentially even inhibiting sleep.

U.S. Pat. No. 6,516,805 (Thorton), as well as its related parentapplication, also describes a system with two halves. It also usesmoldable material to interface with the teeth. A post 16 extends fromthe upper arch 12 and contacts the lower arch 14 to extend the user'smandible. However, this two-half design requires the post to bepositioned at the front of the upper arch. Thus the post may disengagefrom the lower arch when the mouth is opened, causing the mandible to nolonger be in an advanced position. In addition, there's no mechanicalelement to prevent the device from completely closing, causing upperarch and lower arch become co-planar.

U.S. Pat. No. 5,499,633 (Fenton) describes a system with two halves. Itincludes apertures 40 and projections 36. The projections are receivedinto the apertures, therefore creating mandibular extension. However,with this device the upper and lower members are not securely connectedor hinged to one another. The projections are made from the soft,moldable material of the rest of the device, and as such, may bedifficult to engage in the apertures. In addition, the soft material ofthe projections may allow movement between the upper and lower members,thus not consistently advancing the mandible. In addition, the twomembers of the device may easily disengage from the teeth through thenatural movement of the jaw. The device also requires boiling andmolding.

U.S. Pat. No. 1,146,264 (Kelly) describes a dental splint. As bestunderstood, this device use two separate trays to hold the jaw inposition, with the trays apparently cemented to the user's teeth. Thisis used to create a static position if the bones of the jaw arefractured and must heal. It recites pillars 18, which hold the traysapart so that food may be inserted into the user's mouth.

U.S. Pat. No. 4,376,628 (Aardse) describes a tooth-treating mechanism intwo halves It includes parallel ridges 9 and 10. The ridges serve tocenter one device half over the other device half. The orientation ofthe ridges does not create mandibular advancement, as they are in adirection perpendicular to that required for mandibular advancement.

CA 2,177,284 (Voss) describes a one-piece mandibular advancement device.This device is molded from pliable material in one piece and uses asimple hinge mechanism. The hinges 4 and 4′ are comprised of a thinnedcross-section of the molded material, in conjunction with half-cylinder40 and notch 41. This assembly allows the device to bend. This device,however, faces numerous limitations. The simple hinge mechanism issubject to wear as the pliable material is bent over many cycles of theuser's mouth opening and closing. The mandibular advancement the deviceprovides is created solely by the position of the hinge, and facessimilar limitations to the device described in '084 (Bergersen) Inaddition, there's no mechanical element to prevent the device fromcompletely closing, causing upper surface 24 and lower surface 14 tobecome co-planar and therefore restricting airflow through the mouth.

Other mandibular devices are disclosed in patents and in the marketplaceas well. However, all face similar limitations as the above describedinventions. In summary, many of the above devices require fitting,molding, or adjustment by a dental professional and fabricationlaboratory. This process is costly and time-consuming, and prevents bynon-skilled persons using the device straight-out-of-the-package. Stillother systems use a simple hinge that quickly wears and may no longerproperly advance the mandible. Many of these devices also restrict theuser from opening his/her mouth, which many users find undesirable.

BRIEF SUMMARY OF THE INVENTION

Several objects and advantages of the present invention will be madeclear. What is needed is a mandibular advancement device that does notrequire fitting, heating, molding, or adjustment in order to be used.Additionally, a device is needed that's durable, easy to wear, andsimple to use. It should be comfortable and allow the user to freelyopen and close his/her mouth so that natural jaw movement is notinhibited. Further, there's a need for a device that can be usedstraight-out-of-the-package by non-skilled persons, eliminating the needfor costly, time-consuming fitting by a dental professional andfabrication laboratory.

In the preferred embodiment of the invention, a one-piece device ismolded from a flexible thermoplastic elastomer such as Kraton®. Thedevice includes an upper maxillary tray and a lower mandibulary trayconnected by a hinging mechanism. Both upper and lower trays includeinner and outer walls which increase contact area with the teeth. Thelingual surface of the mandibulary tray features a flange which extendsdown into the lingual vestibule to provide greater contact surface toadvance the mandible. The flange is designed to be of a length whichextends into the lingual vestibule but does not contact the lingualfrenulum.

The hinge mechanism of the preferred embodiment includes a positivepositioning system comprised of opposed interlocking ridges. The ridgesserve to create and maintain offset between the position of the uppertray and lower tray relative to each other, therefore advancing theuser's mandible. The location of the ridges, close to the hinge points,is also advantageous because the ridges continue to engage one anotherand therefore advance the mandible even when the jaw is almost entirelyopen. Further, the ridges are self-aligning and easily engage withvirtually no chance of jamming.

The preferred embodiment also includes posts located near the front ofthe upper tray and the lower tray. These posts create an air gap thatprevents the upper tray and lower tray from completely closing againstone another. The preferred embodiment is also contoured and curved tocomfortably fit in the mouth and on the teeth. Related to the contouringis a cleft notch on the upper front of the maxillary tray to avoidrubbing and irritation to the connective tissue (maxillary labialfrenulum) on the inside of the upper lip.

DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a perspective view of the device in the open position, whennot in the user's mouth

FIG. 2 a is a top view of the device

FIG. 2 b is a bottom view of the device

FIG. 3 a is a right side view of the device

FIG. 3 b is a left side view of the device

FIG. 4 a is a back-end view of the device

FIG. 4 b is a front-end view of the device

FIG. 5 is a bottom view of the front section of the lower tray of thedevice

FIG. 6 is a perspective view of the front section of the lower tray ofthe device

DESCRIPTION OF THE REFERENCE NUMERALS

-   10 overall device-   12 upper maxillary tray-   14 lower mandibulary tray-   16 a inner wall of upper maxillary tray-   16 b outer wall of upper maxillary tray-   18 a inner wall of lower mandibulary tray-   18 b outer wall of lower mandibulary tray-   18 c lingual flange portion of inner wall of lower mandibulary tray-   20 a right post-   20 b left post-   21 a right retention post-   21 b left retention post-   22 a overall hinge right-   22 b overall hinge left-   24 a forward upper interlocking ridge right-   24 b aft upper interlocking ridge right-   24 c lower interlocking ridge right-   26 a forward upper interlocking ridge left-   26 b aft upper interlocking ridge left-   26 c lower interlocking ridge left-   28 a flexible hinge section right-   28 b flexible hinge section left-   32 outer tray wall chamfer-   34 curved contour of upper maxillary tray-   36 curved contour of lower mandibulary tray-   38 cleft contour-   40 tooth retention tab

DETAILED DESCRIPTION

In all figures, the device is shown in the open position, when not inthe user's mouth.

FIG. 1 is a perspective view of the preferred embodiment of theinvention. As can be seen, the one-piece overall device 10 folds atoverall hinge right 22 a, and overall hinge left 22 b. Upper maxillarytray 12 and lower mandibulary tray 14 are both u-shaped, joined togetherby hinges 22 a and 22 b. The length of the upper and lower trays arepreferably designed so that the device extends back to the centers ofthe upper first molars when fully inserted. This allows for amplecontact between the trays and the teeth to maintain device positioning,but doesn't extend too far into the mouth so as to create discomfort orpromote gagging.

FIG. 1 also shows the interlocking ridges of each hinge. Forward upperinterlocking ridge right 24 a, aft upper interlocking ridge right 24 b,lower interlocking ridge right 24 c, together form the positiveengagement system. The preferred embodiment uses ridges that aretrapezoidal in cross-section. This shape creates a chamfered profilethat easily lets lower ridge 24 c mesh with upper ridges 24 a and 24 bas the device is closed. This is identical for the left side hinge 22 b.The molded material is thinnest in cross-section on the overall deviceat flexible hinge section right 28 a and flexible hinge section left 28b. The thinned cross-section permits the device to flex and bend as ahinge. The hinge also acts as a low-force spring, with the force of thesprings aiding to keep the upper tray 12 in contact with the user'smaxillary teeth, and lower tray 14 in contact with the user's themandibulary teeth.

FIG. 1 also shows right post 20 a and left post 20 b. These postsprevent upper maxillary tray 12 and lower mandibulary tray 14 fromclosing against each other completely. Of course, said posts could beplaced elsewhere on the device, such as an identical location on tray14. Posts 20 a and 20 b may be located in different positions on eithertray, however the location shown offers advantages of being furtherideally located to maintain airflow. Right retention post 21 a and leftretention post 21 b serve similar function to posts 20 a and 20 b. Allposts further serve by: providing additional support for theirrespective tray, minimizing flex and bending for their respective tray,and correcting overall angulation as each post contacts its opposingtray.

FIG. 2 a is a top view of the device, further showing the locations ofthe all of the interlocking ridges, as well as all posts.

FIG. 2 b is a bottom view of the device, further showing the toothretention tab 40.

FIG. 3 a is a right side view of the device, further showing thelocations of one side of interlocking ridges, as well as posts. Alsoseen is the outer wall of upper maxillary tray 16 b, inner wall of lowermandibulary tray 18 a, and outer wall of lower mandibulary tray 18 b.Outer tray wall chamfer 32, curved contour of upper maxillary tray 34,and curved contour of lower mandibulary tray 36 are all also apparent.18 c shows the lingual flange portion of the inner wall of the lowermandibulary tray. The flange 18 c serves to extend into the user'slingual vestibule to provide greater contact surface for advancing themandible.

FIG. 3 b is a left-side view of the device, showing similar features toview 3 a

FIG. 4 a is a view from the back-end of device.

FIG. 4 b is a view from the front-end of device. Cleft contour 38 isvisible in this view.

FIG. 5 is a bottom view of the front section of the lower tray of thedevice. In this view, tooth retention tab 40 is visible.

FIG. 6 is a perspective view of the front section of the lower tray ofthe device. In this view, tooth retention tab 40 is visible.

Overall device 10 readily bends in half at hinges 22 a and 22 b. It isthen inserted into the user's mouth, with the user's maxillary teethpressing into upper maxillary tray 12 and the user's mandibular teethpressing into lower mandibulary tray 14. The user's maxillary teeth arecradled by the inner wall of upper maxillary tray 16 a and the outerwall of upper maxillary tray 16 b. The user's mandibular teeth arecontacted by the inner wall 18 a of lower mandibulary tray 14, and inaddition, the outer wall 18 b of the tray 14 may contact the maxillaryteeth. The opposing forces of the contact with the facial surface of theupper maxillary dentition and in particular the contact of the innerflange of tray 18 a to the lingual surface of the lower lingualdentition maintain the mandible in a forward position relative to themaxilla, whereby the airway passage in the nasopharynx, oropharynx andlaryngopharynx are kept substantially free of occlusion, thus reducingor eliminating snoring and/or OSA.

The position of the two trays relative to each other, or offset, isdetermined by the location of overall hinges 22 a and 22 b. The offsetis further reinforced by the pairs of hinged ridges, 24 a, 24 b, 24 c,and 26 a, 26 b, 26 c. At the device bends and is placed in the user'smouth, the ridged hinges engage and further reinforce the offset. Theridges continue to engage as a user partially or even fully openshis/her mouth. The location of the ridges, close to the hinge point,allows the ridges to stay engaged over a wider range of mouth motionthan if the ridges were located closer to the front of the overalldevice. It is therefore advantageous to incorporate the ridges into thehinge portion of the overall device. Further, the interlocking ridgeshelp prevent side to side and rotational motion between the upper andlower trays, thereby maintaining alignment.

In the preferred embodiment, the right and left lower interlockingridges, 24 c and 26 c respectively, may be formed such that the highestpoint of each ridge is co-planar with the larger planar surface of lowermandibulary tray 14. This effectively creates a small recess for eachridge, 22 a and 22 b, to engage into, thereby creating a more positiveengagement which helps insure the desired mandibular advancement isachieved. Alternately, ridges 24 c and 26 c may be more simply formedsuch that they are raised above the planer surface of tray 14.

While the preferred embodiment shows a one-piece, living-hinge design,other types of hinges designs could be employed as well. In alternateembodiments, the upper and lower trays could be made as separate piecesand joined together by separate hinge pieces. Alternatively the hingingmechanism could be made of the same or completely different type ofmaterial including but not limited to alloy, metal, plastic,polyethelene, etc.

Another inventive element of the preferred embodiment are the twoairflow posts 20 a and 20 b located near the front of the uppermaxillary tray 12. These posts create an air gap that prevents theplanar surfaces of the upper tray 12 and lower tray 14 from completelyclosing against one another. This insures air will flow through theuser's mouth, even if the teeth are tightly clenched during sleep.

Optionally, right retention post 21 a and left retention post 21 b maybe included. Posts 21 a and 21 b are shown on lower mandibulary tray 14.When the inventive device is placed in the closed position in the user'smouth, posts 21 a and 21 b help insure that the mandible stays in anadvanced position by engaging against posts 20 a and 20 b and therebyfurther preventing lower tray 14 from moving backward relative to uppertray 12.

Another inventive element which may be optionally included is toothretention tab 40. This tab is located on the inner wall of the lowermandibulary tray 14, in the location seen in FIG. 6 and FIG. 5. This tabis positioned and shaped such that it interfaces with the lingualsurface of the mandibular central incisors. The naturally curved lingualsurface of the mandibular central incisors mates with the retention tab,which helps keep the lower mandibulary tray positioned on the teeth andhelps prevents the tray from sliding off and disengaging with the teeth.

The preferred embodiment is also contoured and curved to comfortably fitin the mouth and on the teeth. The edge of both the upper and lowertrays are chamfered, or otherwise made non-sharp, to be comfortable inthe user's mouth. Related to the contouring is cleft contour 38 on theupper front of the maxillary tray 12 to avoid rubbing and irritation tothe connective tissue on the inside of the upper lip. Likewise, the wallthickness of the device may vary throughout to create an optimal shapefor comfort while maintaining durability.

In the preferred embodiment, the device is molded from an appropriatematerial such as Kraton® polymer. Kraton® polymers provide additionalcomfort and cushion to the user. The rubbery properties of the polymerincrease the amount of surface tension and contact adhesion with theteeth and prevent the device from falling out during use. Kraton®polymers will also wear longer and better than the traditional resinscurrently on the market. Specifically, a Dynaflex® thermoplasticelastomer offers excellent properties for the invention. Of course,other suitable materials could be employed as well, whether in the formof synthetic polymers or even natural rubber.

While the overall device serves primarily for the purpose of mandibularadvancement, with the associated sleep-related benefits, the device alsoserves to reduce problems associated with bruxism, or the grinding ofthe teeth. The mechanism for this is readily apparent, as the upper andlower trays prevent the maxillary and mandibular teeth from makingdirect contact.

The above described elements combine to create a mandibular advancementdevice that does not require custom fitting and is easily usedoff-the-shelf. Although the above specification and related drawingsdescribe a specific embodiment of the invention, this should not beinterpreted as limiting the scope of the invention to these particularelements. The interpretation of the scope of the invention should bedetermined by the claims and their legal equivalents.

1. A mandibular advancement device comprising: an upper maxillary tray,said upper tray including an inner wall and an outer wall; a lowermandibulary tray, said lower tray including an inner wall and an outerwall; two hinged sections which connect said upper tray to said lowertray, said hinged sections including positioning means for furtherengaging said lower tray with said upper tray.
 2. The device of claim 1in which the positioning means are interlocking ridges.
 3. The device ofclaim 1 which further includes a cleft contour on said upper tray. 4.The device of claim 1 which further includes a tooth retention tab onthe inner wall of said lower tray.
 5. The device of claim 1 which ismade from a thermoplastic polymer.
 6. The device of claim 1 in whichsaid hinged sections further function as springs, with the force of saidsprings aiding to keep said upper tray in contact with the user'smaxillary teeth and said lower tray in contact with the user's themandibular teeth.
 7. The device of claim 1 in which said inner wall ofsaid lower tray includes a flange portion, such that in use said flangeextends into the user's lingual vestibule to provide greater contactsurface for advancing the mandible.
 8. The device of claim 1 in whichsaid upper tray and said lower tray extend to the centers of the user'supper first molars when said device is fully inserted.
 9. The device ofclaim 1 which further serves to reduce the effects of bruxism.
 10. Amandibular advancement device comprising: an upper maxillary tray, saidupper tray including an inner wall and an outer wall; a lowermandibulary tray, said lower tray including an inner wall and an outerwall; two hinged sections which connect said upper tray to said lowertray, said hinged sections including positioning means for furtherengaging said lower tray with said upper tray; a plurality of posts toprevent the planar surface of said upper tray from closing completelyagainst the planar surface of said lower tray.
 11. The device of claim10 in which the positioning means are interlocking ridges.
 12. Thedevice of claim 10 which further includes a cleft contour on said uppertray.
 13. The device of claim 10 which further includes a toothretention tab on the inner wall of said lower tray.
 14. The device ofclaim 10 which is made from a thermoplastic polymer.
 15. The device ofclaim 10 in which said hinged sections further function as springs, withthe force of said springs aiding to keep said upper tray in contact withthe user's maxillary teeth and said lower tray in contact with theuser's the mandibular teeth.
 16. The device of claim 10 in which saidinner wall of said lower tray includes a flange portion, such that inuse said flange extends into the user's lingual vestibule to providegreater contact surface for advancing the mandible.
 17. The device ofclaim 10 in which said upper tray and said lower tray extend to thecenters of the user's upper first molars when said device is fullyinserted.
 18. The device of claim 10 which further serves to reduce theeffects of bruxism.
 19. A method of mandibular advancement comprising:engaging the maxillary teeth with an upper maxillary tray, said uppertray including an inner wall and an outer wall; engaging the mandibularteeth with a lower mandibulary tray, said lower tray including an innerwall and an outer wall; connecting said upper and lower trays with twohinged sections, said hinged sections including positioning means forfurther engaging said lower tray with said upper tray.
 20. The method ofclaim 19 in which the positioning means are interlocking ridges.
 21. Themethod of claim 19 in which a cleft contour on said upper tray isfurther included.
 22. The method of claim 19 in which a tooth retentiontab on the inner wall of said lower tray is included.
 23. The method ofclaim 19 in which said trays and other components are made from athermoplastic polymer.
 24. The method of claim 19 in which the hingedsections further function as springs, with the force of said springsaiding to keep said upper tray in contact with the user's maxillaryteeth and said lower tray in contact with the user's the mandibularteeth.
 25. The method of claim 19 in which said inner wall of said lowertray includes a flange portion, such that in use said flange extendsinto the user's lingual vestibule to provide greater contact surface foradvancing the mandible.
 26. The method of claim 19 in which said uppertray and said lower tray extend to the centers of the user's upper firstmolars when said device is fully inserted.